You can set up as many users as you like, but there’s a limit to how many users have a "seat". 

When a user is given a seat by an administrator, then they are allowed to log in and use The maximum number of seats is dependent upon the product tier you have purchased. 

If you need more user seats you can upgrade at any time. As an administrator you can check how many user seats are filled and your maximum total on your administrator page.

Click here for more details on how to create new Users